For many years, the familiar “horsehead” walking-beam type mechanism has been used for pumping fluids such as water and/or oil from subterranean formations. As discussed at length in commonly assigned co-pending U.S. patent application Ser. No. 11/761,484, titled “Linear Rod Pump Apparatus And Method,” by Beck et al., conventional walking beam apparatuses have a number of disadvantages, not the least of which is their large size. In addition, performance of the walking beam pump apparatus is largely a function of the design in connection of a number of mechanical parts, which include massive counter-weights and complex drive mechanisms which are difficult to control for obtaining maximum pumping efficiency or to compensate for changes in the condition of the well over time.
Also, for potential well sites in very remote locations, and particularly in locations without access to a power grid and no practical road access for regularly servicing a pumping apparatus or a motor generator, batteries, or other traditional stand-alone power source for a pumping apparatus, it has heretofore been impractical, and in some cases impossible, to utilize a conventional walking-beam apparatus or other known types of prior pumping apparatuses and methods. As a result, potentially valuable energy resources have remained untapped.
Although the linear rod pump apparatus and methods, disclosed in the above-referenced '484 to Beck, provide significant improvement over other prior pumping apparatuses and methods in many pumping applications, the continually reversing motor utilized in the linear rod pump apparatus and methods disclosed in Beck '484 may not be desirable in some pumping applications. For such applications, another type of apparatus and method which could operate without continually reversing the motor might prove to be more desirable.
It is particularly desirable to provide such an improved apparatus and method for pumping fluid from hydrocarbon wells, or other fluid reservoirs, which are located so remotely from any source of line power or access roads that the only convenient source of energy for powering the pumping apparatus in an unattended mode would be a solar array. It is particularly desirable, in this regard, for some applications to have the solar array be the sole source of power, without the need for reliance upon any back-up batteries or other capacitive energy storage.